From the 1830s each new Latin American republic goes its own way, though often distracted by border conflicts with neighbours.

Subsequent events suggest that Spain has left her colonies ill-equipped for self-rule. Small privileged groups of Europeans and mestizos, supported by the forced labour of illiterate peasants, incline naturally to oligarchy as a political system. But centuries of authoritarian rule by Spain have not prepared these oligarchs to transfer power among themselves peacefully (as happens through the centuries, for example, in oligarchic Venice).

The result is a pattern of prevailing political chaos in which the ambitions of ruthless leaders can be seen sometimes as the cause of the problem and sometimes as a temporary solution.

Strong men of this kind, frequently emerging from the army, are such a characteristic part of the region's political life that Latin America has its own word for them. They are caudíllos, and the very specific loyalty which they inspire in their followers is the cult of personalismo.

Simón Bolívar, the hero of Latin American independence, is a prototype of the caudíllo. In opposition to Spanish oppression his autocratic tendencies seem all on the side of virtue. But as president of the liberated republics, while shunning any trappings of monarchy, he is not at all averse to assuming the useful powers of a dictator.

The 19th and early 20th centuries produce numerous examples of the caudíllo in Latin America. The best known in recent years is Argentina's Perón, who with the support of his wife Eva carries personalismo to exceptional lengths. By the end of the 20th century, with the subcontinent progressing in fits and starts towards democracy, military juntas rather than individual caudíllos tend to be the problem.

The caudíllos usually pay lip service to one or other of the two factions which are the consistent features of Latin American politics. On one side are the liberals, campaigning for secular education and some degree of redistribution of wealth by land reform. On the other are the conservatives, seeking to preserve the central role of the church together with an economic status quo characterized by profound inequality (see Liberals and Conservatives).

In most of the republics, for most of the time, the conservatives prevail. Latin America enters the 20th century with social structures still in many ways characteristic of the colonial era.

World Wars and Depression: 1914-1945

In the early 20th century the USA begins to take a more interventionist role in the internal affairs of the Latin American republics - in what becomes known locally as yanqui imperialism. In the interests of preserving regional stability, US marines are sent by President Taft into Honduras in 1911 and Nicaragua in 1912, and by Woodrow Wilson into Haiti in 1915 and the Domininican Republic in 1916.

Resentment against an overbearing neighbour is one of the reasons why the Latin American nations remain largely uninvolved in World War I. Only eight of the twenty republics declare war on Germany. Only Cuba and Brazil provide active support for the allied cause.

The war years bring economic benefits to the republics as the suppliers of raw materials, but the world-wide depression from 1929 has a correspondingly disastrous effect. The crisis, together with the influential example of fascism in Europe, brings to several of the Latin America nations a marked renewal of the caudíllo tradition, now transformed more explicitly into military dictatorship.

However the relationship with the US shows a simultaneous improvement. In 1928 Herbert Hoover makes a goodwill visit to Latin America. In 1933 Franklin Roosevelt rules out unilateral intervention in Latin American affairs, inaugurating what he describes as a Good Neighbour policy.

The result is that Latin America is much more supportive of the USA in the next global conflict. Within two months of Pearl Harbor eighteen of the twenty republics have either declared war on the Axis nations or have severed diplomatic relations. Only Argentina, with a fascist regime of its own in power, delays declaration of war until the last possible moment in 1945.

The support of most of the republics is limited to the provision of food and raw materials (bringing another period of prosperity to the region). But Brazil sends a force to fight in the Mediterranean. And a Mexican air squadron is engaged in the Pacific.

Juntas and cartels: from1945

Although the gradual trend in Latin America in the second half of the 20th century is towards greater democracy, parts of the subcontinent are severely disfigured during the period by a return of singularly brutal military regimes and by the emergence of drug cartels.

The Somoza dynasty in Nicaragua is the longest lasting of the local dictatorships. Anastasio Somoza seizes power in 1936 and is succeeded by two of his sons before the years of corrupt family rule are finally ended in 1979. The first of the postwar military regimes is in Paraguay, where the commander of the armed forces, Alfredo Stroessner, instals himself as president in 1954.

In this same year, 1954, a military junta is installed in Guatemala in a coup organized by the CIA. Under a succession of military rulers the country is soon plunged into a nightmare of terror and death squads.

Haiti, in 1957, elects its own tyrant in the disarming guise of a country doctor, François Duvalier. The Haitians soon have cause to regret their trust in Papa Doc. The next republic to succumb to a coup is Bolivia, where the military government installed in 1964 is sufficiently repressive for Che Guevara to decide, in 1966, that this is the most promising place in Latin America to launch a Marxist revolution.

The year 1973 brings appalling regimes to Uruguay and Chile, two republics which have previously achieved a better democratic record than most of their neighbours in Latin America. A military takeover in Uruguay results from the need to suppress a group of urban guerillas, the Tupamaros. And a violent coup in Chile, sponsored by the CIA, is the result of the perceived need in Washington to remove an elected Marxist government.

The list of shame ends with the two most recent generals to seize power and to maintain it with terror and torture - Videla in Argentina in 1976 and Noriega in Panama in 1983.

The USA, as head prefect of the continent, is discreetly involved (through the CIA) in almost everything that happens in these unstable republics. The only successful Communist coup in the hemisphere, in Cuba in 1959, leaves Washington obsessively nervous about Marxist infiltration among its neighbours. The result is US intervention against left-wing governments in Guatemala in 1954, in Chile in 1973 and in Nicaragua in 1984.

With hindsight, after the end of the Cold War, US apprehensions seem exaggerated. But an extremely dramatic intervention in 1989, involving the occupation of a capital city and the arrest of a head of state, relates to a problem which is likely to prove more intractable than Marxism.

In December 1989 George Bush sends 24,000 US troops into Panama to seize the local dictator Manuel Noriega. The reason is his suspected involvement with the unquenchable flow of illegal drugs from Latin America into the USA.

From the 1970s there is a steady increase in the USA in the use of cocaine and more recently crack, both derived from the coca plant grown in several Latin American countries (particularly Bolivia and Colombia). The trade in these substances, bringing huge profits to the drugs cartels and much laundering of illegal funds, is a profoundly corrupting influence in central America. Unresolved high-level political murders in Mexico in the mid-1990s are possibly drug-related.

Return to democracy: late 20th century

From the mid-1980s nearly all the Latin America republics, discarding their military regimes, contrive an often painful return to democracy (painful because in countries such as Chile the longing for revenge, by the relatives of those who have 'disappeared', clashes with the amnesty arranged for themselves by the retiring generals).

By the end of the century political parties, in nearly every country, are contesting elections at regular intervals without military interference. Corruption and chaos, long endemic in many parts of Latin America, cannot everywhere vanish overnight. But the situation looks brighter than ever before, in spite of financial crises in major economies such as Mexico and Brazil.